Breathing apparatus



2 Sheets-Sheet l ATTORNEYS April 23, 1946. P, E. MEIDEVNYBAUER, JR

BREATHING APPARATUS Filed Nov. 19, 1942 y pom A ril 23, 1946. P. E.MEIDENBAUER, JR 2,399,054

BREATHING APPARATUS Filed Nov. 19, 1942 2 Sheets-Sheet 2 iNVENTOR Nw w aw mm 3N @244 6: Wawm&

ATTORNEYS Patented Apr. 23, 1946 UNITED STATES BREATHING APPARATUSPhillip E. Meidenbauer, Jr., Lancaster, N. Y., assignor to ScottAviation Corporation, Lancaster, N. ,Y., a corporation of New YorkApplication November 19, 1942, Serial No. 466,165

5 Claims.- This invention relates to a breathing apparatus which is moreparticularly designed for use by aviators or aeronauts to supply oxygenwhen flying in high altitudes, but this apparatus may also be employedadvantageously by miners, firemenand others for supplying oxygen orother life preserving fluid when operating in an atmosphere containingnoxious or poisonous gases.

It is the object of this invention to provide an improved; apparatus ofthis'character in-which the pressure of the oxygen -at which it issupplied from asuitable source is first reduced bya pressure reducingvalve mechanism to a pressure which can be more easily controlled-andthen delivered to the user by a gas demand valve mechanism whichoperates in response to the breathing action of the user.

A further object of this invention is to providean instrument foraccomplishing this purpose which is very compact in construction, re-

liable in-operation and not liable to get out of order.

- In the accompanying drawings:

Fig. 1 is a top plan view of this improved breathing apparatus, on areduced scale. Fig. 2 is a vertical transverse section of the same, onan enlarged scale, takenon lines 2--3, Figs-l and fi, lookingrearwardly. I Fig.3 is a similar view taken on the same line lookingforwardly.

r Fig. 4 is a fragmentary-cross section of the demand valve mechanismtaken generally on line 4-4, Fig; 2. l

Fig. .5'is: a vertical transverse section, on 'an enlarged scale, takenon lines 55, Figs. 1 and 6 looking rearwardly.

Fig. 6 is a-vertical longitudinal section, taken on linesv 6-6, Figs. 2and 5, and showing the inlet of the delivery. chamber closed and itsoutlet open. 7 y

Fig. 7 is a fragmentary verticalsection, on an enlarged scale, of thepressure reducing valve and associated parts.

- In the following description the reference nu-.

merals indicate corresponding parts in the several'figures of thedrawings.

The numeral l represents the main hollow enclosing case or housing ofthe apparatus upon which the various working elements of the apparatusare mounted and which preferably has the form of a cylinder the frontside of which is "open and comprises a cylindrical side wall- I I,

aaflat rear wall [2 arranged at the rearedge of the side wall and formedintegrally therewith by casting or. otherwise, and a front wall 13preferably constructed of sheet metal and detachably connected with therespective part of the side wall by an annular flange I4 projectingrearwardly from the edge of the front wall and engaging with the cylindricalperiphery of the side Wall to which it is secured by screws 14!.

Any suitable means may be employed for releasably mounting this body onthe harness worn by the aviator'such, for example, as the clip I5attached to the rear wall ofthe body and adapted to grasp a beltor-s'trap on thebody; of the aviator. V f p 3 i The spacewithin'theenclosing case is divided by a partition having the form of abody l9 into sists of a block of metal lllwhich is arranged withinthecase and hasits lower end resting on the bottom thereof and'one ofits 'sides arranged- 'adjacent to a side of this case. On its undersidethe partitionbody is provided with a neck 20 which projects downwardlythrough an opening 2| in the bottom of the case side wall and onitslateral side the same is provided with an inacternally threadedsocket 22"into which the externally threaded inner end of a-tubular body23 of areplenishing check valve is screwed so as to project laterallytherefrom through an opening 24 in the adjacent part of the case sidewall.

The partition body is secured firmly to the case side wall by screws 25and airtight joints are produced between the same and the case. wall bygaskets or soft washers 26, 2-1 surrounding the neck 2|] and the valvebody 23. and clamped between the respective parts of the case side walland the partition'body I9, as shown in Figs. 2 and 5. The partition body19 forms the stationary wall of'the receiving chamber IS, the open innerside of which communicates with a flexible diaphragm 60 bellows 28 whichis capable of. expanding and contracting. The inner. end of this bellowsis fixed and connected to asupporting ring 29 mounted on the, partitionbody around the receiving chamber. The outer=movab1e endof the bellowsdiaphragm is connected to an external a receiving chamber ltwhichreceiv'es the oxy-' flange 30 formed at the outer end of a tubularplunger 3| arranged within the bellows. A gasket 32 is interposedbetween the supporting ring 29 and the partition body and these membersare detachably connected with each other by screws 33.

Pressure reducing means are provided which are responsive to themovement of the bellows and permit oxygenstored in a: portable eontainerunder relatively high pressure to enter the receiving chamber at areduced pressure, which means are preferably constructed as follows:

The portable oxygen container has the form of a metal bottle I! theupper end of which has a hollow neck 43 which is detaohablyconnectedwith the neck of the partition body'by a screw joint. A supplypassage 34 extends lengthwise through the partition neck from the bottleto the receiving chamber. In aviation the pressure in the bottle [1 orother source from which the re ceiving chamber i6 is supplied withoxygen may be five hundred pounds which is too high for direct use bythe aviator and it is therefore necessary to reduce the pressure of theoxygen in the receiving chamber to, say, twenty. pounds in order that itcan be handled safely, conveniently and comfortably by the aviator. Forthis purpose a reducing valve mechanism is employed which includes avalve tube 35 arranged in the passage 34 and provided with an inwardlyfacing external shoulder 36 which bears against a gasket 31 interposedbetween this shoulder and an outwardly facing shoulder 38 in saidpassage and provided at its inner end with a valve seat 40 whichsurrounds the longitudinal port or passage 39 in the valve tube. Thevalve tube is. held in place by a tubular clamping nut 41 screwed intothe passage 34 and bearing against the outer end of the valve tube and atubular lock nut 42 screwed into the passage and engaging with the outerend of the clamping nut 4|. as shown in Fig. 5. Within the inner part ofthe passage 34 is arranged a longitudina-lly movable reducing valve orclosure 45 the outer end of which is providedwith a valve disk 46adapted to engage with the seat 40 on the valve tube and the inner endof which projects into that part of the oxygen receiving chamber withinthe partition body. Upon moving the clo'- sure or reducing valve 45inwardly away from the seat 40 the port 39 is uncovered and oxygen ispermitted to flow from the" bottleinto the receiving chamber l6 and uponmoving the valve outwardly and against the seat 40 the flow of oxygen isshut off. The valve .45 fits into the passage 34 loosely so as to permitthe oxygen to flow past the same, and to prevent any oxygen in this passage from interfering with the free movement of this valve a reliefpassage is provided in the partition body which extends from thereceiving chamber to the passage 34 adjacent to the outer end of thereducing valve, which relief passage preferably comprises two verticalsections 41 formed in the partition body 49 on opposite sides of thepassage 34 and opening at their upper ends into the receiving chamber l6and a horizontal section 41! formed in the partition body and having itsinner part communicating with the lower ends of the vertical sections 41and the valve passage 34 adjacent to the lower end of the valves 45 andhaving its outer end closed by a screw plug 412, as shown in Figs. Sand7. The reducing valve is yieldingly moved upwardly into an open positionin which it uncovers the port 33 by a spring 45! which is preferably ofspiral form and rests at one end on the bottom of the receivin chamberl6, while its opposite end is connected with the upper end of thereducing valve, as best shown in Fig. 7.

The numeral 48 represents a vertical supporting bar which is secured tothe ring 29 so as to extend across the opening in the latter and thusmaintain communication between the receiving chamber "5 in the partitionand the interior of the bellows. The inward movement of the plunger 3|is limited by engagement of its inner end with the outer side of thesupporting bar 48 which acts as a stop for this purpose, as shown inFig. 5. The plunger is moved inwardly and held yieldingly in engagementwith the supporting bar 48 by adjusta'ble spring means which in theirpreferred form are constructed as follows:

The numeral 49" represents a helical spring arranged in the plunger andbearing with its inner end against the inner end or closed bottom of thesame. The outer end of this spring is backed up by adjusting andcushioning means which preferably comprise an inner follower 58 engagingthe outer end of the spring 49, an outer follower 50'! bearing againstthe inner end of an adjusting screw 5i, and a cushion 502 of leather orthe like interposed between these followers. The adjusting screw 5!works in a threaded open ing formed in the central part of a supportingbracket 52 of U-shape which is secured to the inner bellows ring 29 bythe same screws 33 which connect this ring to the partitionbody l3, asshown in Figs. 2 and 5. Upon turning this screw in one direction thespring 49 will be strengthened and require greater gas pressure withinthe bellows to expand the same outwardly, while turn ing of this screwin the opposite direction this spring will be weakened and require lessgas pressure inside the bellows to expand the same.- After theresistance of the spring 49 has been adjusted the screw 51 is heldagainst turning by a jam nut 53 onthis screw and bearing against theadjacent part of the bracket 52. The cushion 502 prevents vibration ofthe apparatus from affecting the adjustment of the spring 49.

The numeral 54 represents a shifting rod passing through a guide openingin the supporting bar and secured at its outer end to the inner end ofthe plunger while its inner end is arranged within the receiving chamber[6. Within the latter is arranged an L-shaped lever which turns in avertical plane and has a lower horizontal'arm 56 bearing against theupper end of the valve 45 and an upper vertical arm 61 providedwith anopening through which the shifting rod 54 passes. The lower arm 56 isarranged between two lugs 59 projecting inwardly from the lower part ofthe vertical bar 48 and is pivoted thereto and the upper arm 51 bearswith its" inner side against anadjustable bearing screw nut 6| which isheld in its adjusted position on the shifting rod 54 by ajam screw nut62.

Whenever the bellows 28 is expanded by the pressure of the gas withinthe receiving chamber IS, the shifting rod 54 rocks the L-shaped lever56, 51 outwardly, whereby the lower arm of this lever forces the valve45 against the seat 40 and prevents the further flow of oxygen gas fromthe bottle I! or other source of supply into the receiving chamber. Whenthe pressure of the fluid in the-receiving chamber l6 drops to apredetermined pressure the spring 49 contacts the bellows and rocks theL-'-shaped lever inwardly thereby permitting the valve 45 to be opened,as shown in Fig. 5, by the pressure of. the spring, 45l and aaeaoseenabling, further fluid. to pass from this supply source intothereceiving chamber. 7 I

By increasing the compression on the bellows spring, 49 it will requirea higher pressure of fluid in the receiving chamberlfi before thereducing valve 45 will be closed and upon decreasing the compression ofthis spring. the reducing valve 45 will close when a lower fluidpressure has been reached in the receiving chamber [6. .For the purposeof preventing any dirt or solid particles from passing from thecontainer I! to the receiving chamber separating means are providedconsisting preferably of a screen 42l which is secured between thetubular screw nuts 4| and 42 and whereby any dirt or the like carried bythe oxygen in the bottle I! is intercepted. and prevented from beinginhaled by the aviator.

Replenishing means areprovided whereby the bottle I! and thefiuidreceivingchamber It may be replenished from an oxygen tank or othermain source in which a comparatively large volume of this fluid isstored and transferred in smaller batches to this breathing apparatusfor, delivery at the proper pressure to the-aviator as required. Thesereplenishing means. in the preferred construction shown in the drawingsare organized as follows:

When replenishing of the supply of oxygen to the receiving chamber I 6from a main supply becomes necessary or desirable the outer end of thevalve body 23 is temporarily connected by a supply hose .63 or the likewith a tank in which a large volume of this gas is stored which gasflows through a longitudinal passage in this valve body to thelongitudinal passage 39 in the reducingvalve tube 35 by a transferconduit consisting of an annular passage 64 formed on the periphery ofthe valve tube 35 within the opening 34 of the neck 20 and communicatingwith the longitudinal passage 39 of the valve tube by a plurality ofradial openings 65 in this tube, and an inclined passage 66 formed inthe partition body 19 and extending from the inner end of thereplenishing valve body 23 to the annular passage 64, as shown in Fig.5.

Within the check valve body 23 is arranged a check valve 61 of anysuitable construction, such, for example, as that commonly used in thefilling nipples of pneumatic tires for automobile wheels, whereby gasunder pressure is permitted to flow forwardly from the main supply tankthrough the passages formed respectively in the replenishing valve body,the partition body and the valve tube 35 to the outlet at the upperendof the latter and to the neck of the bottle 11, but backward flov. ofthis gas through the replenishing valve body is prevented. It istherefore possible by these means to transfer gas from the main storagetank to the bottle and to the passage or port leading to the receivingchamber 16 by merely attaching the hose 63 to the outer end of the valvebody 23 and maintaining such connection until the desired amount ofgashas been admitted to the bottle and the passages connected therewithafter which the hose 63 is detached from the valve body 23, whereby thetransfer of gas will cease and backward flow of gas will beautomatically prevented.

For the purpose of preventing any dirt, dust or large particles frompassing from the main gas supply tank into the breathing apparatus theinner end of the check valve body is provided with a screen 69 whichseparates such material from the; gas and holds it back in the body ofthis valve until theapparatus'can be cleaned, thereby preventing such:material from interfering with the proper functioning of the partswith. which the gas'comes in contact as well as preventing the aviatorfrom inhaling the same. In the preferred construction the screen 69 isseated on a shoulder at the inner end of the socket in thepartition bodywhich receives the body .23 of .the main check valve and is heldthereagainst bya spring I69 interposed between this screen and the innerend of the valve body 23, as shown in Fig. 5.

. In order to enable the aviator or other user of this apparatus toobserve the pressure at which the gas is being supplied to theapparatus, gage means are provided which comprise a pressure responsivegage 10 which may be of any suitable construction and which is mountedon the upper side of the case of the apparatus so that the aviator canconveniently read the indicator of the gage. The mechanism of the gagemay be of the usual pressure responsive type now in common use and abranch tube H may be employed which connects the passage 66 adjacent tothe check valve body 23 with the inner part of the gage, as shown inFigs '2 and 5. This branch tube consists preferably of flexible metal sothat the same can be bent for convenience in assemblying anddisassembling the parts with which the gage. is associated. For thepurpose of preventing excess pressure in the receiving chamber IS asafety or automatic blow-off valve 12 is provided whereby gas will bepermitted to escape from this receiving chamber to the delivery chamberI8 in case the pressure within the receiving chamber rises above apredetermined normal due to leakage. This safety valve may be of usualand well known construction, such as the spring loaded safety valves nowin common use, and the same may be located in any available part of theapparatus but, as shown in Figs. 2, 5 and 6, the same is arranged in anopening formed in the upper part of the partition body l9 and extendingfrom the receiving chamber to the delivery chamber. When therefore anexcessively high pressure exists in the receiving chamber the safetyvalve opens automatically and permits sufficient gas to escape to thedelivery chamber as will reduce thepressure in the receiving chamber tothe desired point. 1

The oxygen is withdrawn from the delivery 'chamber by inhalation of theaviator through themedium of an inhaling apparatus or mask which isapplied to the face of the aviator and which is provided with aninhaling tube 73 of the usual character. When the aviator wishes toinhale oxygen from the delivery chamber the inlet or nozzle M of thisinhaling apparatus is inserted in a tubular socket '55 which is formedin the bore of a bu hing or sleeve 16 mounted on the case of thebreathing apparatus. In its preferred form this sleeve is of cylindricalform and secured in a correspondingly shaped opening Tl in the top ofthe housing by a set screw 13, A gasket 19 is clamped between this caseand a shoulder 83 on this sleeve for producing an air-tight jointbetween the same. When the breathing apparatus is not in use the outletopening in this sleeve is closed by a lid 8| which is connected at onepart of its edge to the adjacent part of the sleeve by means of a hingeconsisting preferably of a pintle 82 passing through companion pivotlugs 55 arranged on corresponding edge portions of the lid 8| and thesleeve 16. This lid is yieldingly'held in a closed position by a helicalspring 83 surrounding the pintle of this hinge and bearing at itsopposite ends against the 11d and the adjacent part of this sleeve.

In order to, use the breathing apparatus the lid is'lifted and thenozzle of the inhaler insorted into the gas outlet of the deliverychamher and during this time the lid is held by the spring 83 againstthe inhaling tube 13, as shown in Fig. 6, and whenever the inhaling tubeis withdrawn this spring automatically closes the lid so as to retainthe oxygen in'the delivery chamber, and prevent any dirt or particlesfrom falling into the unit while the same is not in use.

As depletion of oxygen occurs in the delivery chamber the volume ofoxygen withdrawn is automatically replenished by an oxygen restoringmeans which form a part of the present improvement and which, in thepreferred. form, are constructed as follows:

The numeral 84 represents a gas restoring passage formed in thepartition body l9 and extending from the receiving chamber l6 to thedelivery chamber. This restoring passage is controlled by a demand orcontrol valve mechanism which responds to the suction or vacuum efiectproduced in the delivery chamber by the inhalation of the aviator sothat when the aviator withdraws gas from the delivery chamber acorresponding amount of gas will be automatically permitted, to flowfrom the receiving chamber 16 into the delivery chamber 19 and when thewithdrawal of gas from the delivery chamber ceases then the flowof gasfrom the receiving chamber to the delivery chamber will be automaticallyarrested.

This demand or restoring valve mechanism includes a valve plate 95 whichextends across the outlet end of the restoring passage 84 and is securedto the partition by means of screws 96 threaded into the partition bodyand having washers 81 overlapping this valve plate, as shown in Fig. 4.A gasket 88 is clamped between the margin of this valve plate andthepartition body to form an air-tight joint be-- tween these members.On its inner side the valve plate is provided with an annular valve seat89, and its central part has a valve stem guide openin 99. Between thelatter and the valve seat 89 this'plate has a plurality of gas ports oropenings 9!. On its outer side the valve plate has a cavity forming aspring seat 92. The numeral 93 represents a valve having preferably theform of a disk made of rubber or the like and secured in a cup-shapedhead 94 of metal. The numeral 95 represents a valve stem which has itsinner part secured to the head 94 and passing through the valve 93 andthe central opening in the valve plate While the outer part of thisvalve stem projects outwardly into the central partof. the deliverychamber 19. The valve 93 is yieldingly held by a return spring 96 in aposition in which this valve engages all parts of the seat 99 and thuscloses the restoring passage 84. This spring preferably has the form ofa helical cone which surrounds the inner part of the stem '95 and hasits large inner end engaging the seat 92 while its small outer end issecured to the valve stem 95, as shown in Fig. 6. In the closed positionof the controlling or restoring valve 93 the stem 95 is arranged axiallyin line with the center of the valve seat 89. For securing compactnessthe partition body I9 is provided with a recess 91 on its outer side inwhich the valve plate 85, the restoring valve and the inner or -rearparts of the valve stem andreturn spring 86- are located. These parts.are also. so a'rranged'that the axes of the same are inclined and thevalve stem projects upwardly and outwardly relative to the lower-part ofthe partition body, as shown in Fig. 6. Upon moving the valve stem 95later ally inward relative to the axis or the valve seat 89, the valve93 is rocked so that it turns with the outer part of its edge as afulcrum on the outer part of the seat 89 and the diametrically oppositeinner part of this valve is moved away from its seat, thereby uncoveringthe outlet of the restoring passage 84 and permitting gas to pass fromthe receiving chamber to the delivery chamber. During this tiltingmovement of the 1 valve 93 and valve stem 95, the return spring 96 isdistorted so that when the valve stem is'released the resilience of thespring 99 again returns the valve stem and restoring valve so that thisstem is arranged in its central or normal position and the restoringvalve is closed.

For the purpose of causing withdrawal of gas from the delivery chamberto automatically tilt the restoring valve and open the same a movable Iwall is provided which moves inwardly in response to atmosphericpressure against its outer side while a vacuum is created on the innerside thereof by inhalation of the aviator and thereby actuates the valvestem for opening the restoring valve. This movable wall preferably hasthe form' of a flexible diaphragm 98 of thin rubber, impervious silk orthe like which is arranged within the cover l3 andextends across'theopen end 99 in the corresponding side of the case or housing so thatthis diaphragm forms a wall ofthe delivery chamber l8. On the centralpart of the inner side of this diaphragm it is provided with a bear ingplate I00 having the form of an outwardly dished disk which bearsagainst the outer end of the valve stem. The flexible diaphragm isdetachably secured to the peripheral surface of the case around itsopening 99 by lapping the marginal flange IGI of this diaphragm over anannular groove (92 in this peripheral surface and holding this marginalpart in said groove by means of an annular retaining member I03 whichmay consist of a rubber band, as shown in Figs. 2 and 6, or by a cord, asplit spring ring or the like.

The cover or front wall l3 of the main housing is provided with aplurality of vent openings I94 to permit the external air to act on theouter side of the diaphragm.

In order to cause the gas as it issuesflfrom the restoring passage 84 to,be deflected upwardly toward the outlet tube 15 of the deliverychamber, a deflector I95 is secured in an upright position on the lowerpart of the partition and across the space along the outer side of therestoring valve, thereby preventing this stream of gas, as it issuesfrom the restoring passage 84, from striking the lower part of thediaphragm and interfering with the uniform operation of, the samearoundits entire surface. This deflector is preferably high enough to coverall of-this control valve mechanism except the upper partofthe valvestem 95 and is provided with a notch or slot 205 through which this stemprojects outwardly,

as shown in Figs. 2 and 6.

In using this apparatus the aviator attaches the same to the breastportion of his harness by sure has been attained in accordance with theshowing on the pressure gage or indicator 10. The aviator then detachesthe hose from the filling valve 23 which leaves him free to move aboutthe plane and operate the same.

Upon reaching the higher altitudes in his flight and when the airbecomes rarified or deficient in oxygen the aviator inserts the nozzle73 of his inhaling tube into the outlet 15 of the delivery chamber andthen, by inhaling, withdraws oxygen from the delivery chamber to theinterior of the aviators mask. While oxygen is withdrawn by inhalationfrom the delivery chamber l8 the latter is replenished from thereceiving chamber IS in the same measure as the aviators demand ornecessity requires by the automatic opening of the restoring or controlvalve 93 which results from the inward movement of the diaphragm I underatmospheric pressure so long as the aviator continues to inhaleoxygenfrom the delivery chamber. When this inhalation ceases the recoil of thespring 95 causes the valve stem 95 to push the diaphragm outwardly andto close the controlling or restoring valve 93, thereby stopping thefurther flow of oxygen gas from the receiving chamber to the deliverychamber. This operation is repeated as often as is found necessary tomaintain the aviator in safe and comfortable condition.

As a whole this apparatus is very light in weight, yet strong inconstruction and very sensitive in its operation and reliably furnishesthe aviator with oxygen as required.

I claim as my invention:

1. A breathing aparatus comprising a case having side and bottomopenings, a body secured to the inner side of said case and having aneck projecting outwardly through one of said openings and provided witha receiving chamber and a plurality of intercommunicating conduits oneof which is arranged in said neck, another one adapted to communicatewith said receiving chamber and another extending to the side of saidbody in line with the other opening in the case, an oxygen bottleconnected with said neck, a check valve having a body arranged in thelast mentioned opening of said case and adapted to connect anddisconnect the conduit in the adjacent part of the body with a source ofoxygen, and a reducing valve mechanism for controlling the flow ofoxygen from said conduits into said receiving chamber.

2. A breathing apparatus comprising a case having side and bottomopenings, a body secured to the inner side of said case and having aneck projecting outwardly through one of said openings and provided witha receiving chamber and a plurality of intercommunicating conduits oneof which is arranged in'said neck, another one adapted to communicatewith said receiving chamber and another extending to the side of saidbody in line with the other opening in the case, an oxygen bottleconnected with said neck,

a check valve having a body arranged in the last mentioned opening ofsaid case and adapted to connect and disconnect the conduit in theadjacent part of the body with a source of oxygen, a reducing valvemechanism for controlling the fiow of oxygen from said conduits intosaid receiving chamber, and a screen extending across the passage insaid check valve body.

3. A breathing apparatus comprising a case having side and bottomopenings, a body secured to the inner side of said case and providedwith a receiving chamber and a plurality of intercommunicating conduits,one of which is in line with said bottom opening in the case and anotherbeing in line with the side opening thereof, an oxygen bottle connectedwith the conduit which is in line with said bottom opening, check valvemeans adapted to connect and disconnect this conduit in line with theside opening with a source of oxygen, and a reducing valve mechanism forcontrolling the flow of oxygen from said conduits into said receivingchamber.

4. A breathing apparatus comprising a case having an outlet in its top,an opening in its bottom and an opening in its side, a body secured tothe inner side of the case andforming between the body and the case adelivery chamber communicating with said outlet and also containing areceiving chamber, a bottom conduit in line i with said bottom openingand a side conduit communicating with said bottom conduit and arrangedin line with said side opening, an oxygen bottle connected with saidbottom conduit, a check valve mechanism connecting said side conduitwith a source of oxygen, a regulating diaphragm forming a wall of saidreceiving chamber, and a pressure reducing valve mechanism controllingthe flow of oxygen from said conduits to said receiving chamber andactuated by said regulating diaphragm.

5. A breathing apparatus comprising a case having an outlet in its top,an opening in its bottom and an opening in its side, a body secured tothe inner side of the case and forming between the body and the case adelivery chamber communicating with said outlet and also containing areceiving chamber, a bottom conduit in line with said bottom opening anda side conduit communicating with said bottom conduit and arranged inline with said side'opening, an oxygen bottle connected with said bottomconduit, a check valve mechanism connecting said side conduit with asource of oxygen, a regulating diaphragm forming a wall of saidreceiving chamber, a pressure reducing valve mechanism controlling theflow of oxygen from said conduits to said receiving chamber and actuatedby said regulating diaphragm, and a demand valve mechanism whichcontrols the flow of oxygen from the receiving chamber to said deliverychamber and which is responsive to variations in pressure in saiddelivery chamber.

' PHILLIP E. MEIDENBAUER, JR.

